1. Field of the Invention
The present invention relates generally to a connector used in optical fiber mechanical splicing and, more particularly, to a field-installable connector including a stub optical fiber having a laser shaped endface.
2. Description of the Related Art
Optical fibers are used for a variety of applications including voice communication, data transmission and the like. With the ever increasing and varied use of optical fibers, it is apparent that more efficient methods of splicing optical fibers are required. In order to effectively couple the signals transmitted between respective optical fibers, the method of splicing the optical fibers must not significantly attenuate, reduce or alter the transmitted signals. Currently, there are two common methods for splicing optical fibers: fusion splicing and mechanical splicing. Mechanical splicing, the method employed in the present invention, is a process for mating the ends of a pair of optical fibers in which the ends are brought into physical contact with each other and held in place by a mechanical force, such as a “cam” locking mechanism, a spring or a crimp.
Conventional mechanical splicing methods typically involve filling any gap between the endfaces of the fibers, referred to herein as a “core gap,” with a refractive index-matching gel. The gel acts as a medium that aids in the transfer of light between a pair of optical fibers, such as a field optical fiber and the stub optical fiber of a field-installable connector. Even though mechanical splices generally provide acceptable signal transmission characteristics, a mechanical splice can refract and/or disperse a portion of the transmitted signal so as to produce a corresponding return loss. The refractance and/or dispersion is/are due, at least in part, to differences between the respective indices of refraction of the cores of the field optical fiber and the stub optical fiber stub, and the index of refraction of the air in the core gap. The index of refraction of the index-matching gel is selected to match the indices of refraction of the cores of the fibers, and thereby reduce or eliminate the difference between the indices of refraction of the cores of the fibers and the core gap.
To create a conventional mechanical splice, the ends of two optical fibers are typically cleaved and inserted into a mechanical splice assembly having precision fiber alignment features, such as machined or etched “V-grooves” extending longitudinally through the assembly. The number of V-grooves and their respective dimensions are of a size to permit the fibers to rest securely within the assembly. The fibers are cleaved using a mechanical cleaver that produces a substantially flat fiber endface essentially perpendicular to the longitudinal axis of the fiber. Mechanical cleaves/cleavers suffer from several disadvantages. First, mechanical cleaves have an inherent glass defect zone that is a result of the mechanical blade striking the glass fiber. Second, mechanical cleavers typically produce sharp edges between the cleaved endface and the outer diameter of the fiber. This sharp edge can skive the V-grooves of the mechanical splice assembly. Third, mechanical cleavers typically produce substantially flat fiber endfaces with cleave angles that may not be perpendicular to the longitudinal axis of the fiber. The cleave angle may increase the core gap that results when two cleaved fibers are butted together in the mechanical splice assembly without regard for the orientation of their cleave angles, which increases attenuation. In addition to these disadvantages, mechanical cleavers require periodic replacement of the cleaver blade and are not conducive to automation due to long-term instability.
It is known to use a focused relatively low-power laser beam to cut an optical fiber or to fuse together a pair of optical fibers. The use of a laser for processing optical fibers is repeatable and conducive to automation. Laser processing of optical fibers is also known to produce an optical fiber endface that is substantially free of defects, as compared to optical fibers that have been mechanically cleaved. Accordingly, it would be desirable to process a stub optical fiber of a field-installable connector using a laser to overcome at least some of the disadvantages described above. In particular, it would be desirable to laser process the stub optical fiber of a field-installable connector to produce a convex endface substantially free of defects and having an edge radius that aids fiber insertion into a mechanical splice assembly, thus minimizing skiving of alignment features. It would also be desirable to laser process the stub optical fiber to thereby minimize the core gap in a mechanical splice, even in applications in which a field prepared fiber has an endface with a slight angle relative to its longitudinal axis. Further, the laser process should expend no consumables and be automation friendly and stable.